The present invention is related to Japanese patent application No. Hei. 11-343124, filed Dec. 2, 1999; the contents of which are incorporated herein by reference.
The present invention relates to a controller for an internal combustion engine, and more particularly, to a controller for an internal combustion engine having an improved method of stabilizing combustion of an internal combustion engine.
In an engine for burning a mixture by stratified charge combustion such as a direct-injection engine, the mixture forms lumps and the lumps move. As disclosed in JP-A No. H11-2172, there is a technique disclosed using a plurality of spark plugs in each cylinder. When reduction in torque is requested, ignition timing is set behind a normal timing, and the mixture is ignited by a spark plug disposed in a position where a lump of the mixture passes, thereby preventing deterioration of combustion.
As disclosed in JP-A No. H6-229297, in an engine controlling the strength of a swirl flow or the strength of a tumble flow in a cylinder, when engine speed is lower than a target idle speed, the strength of the swirl flow or the strength of the tumble flow is enhanced to stabilize combustion, thereby controlling the engine speed to the target idle speed.
In recent years, however, a higher performance engine is requested to assure stable drivability by always stabilizing combustion under any operating condition. Even when combustion under the specific operating conditions as described above is stabilized, combustion cannot be stabilized under various operating conditions other than the specific operating conditions. The request of assuring the stable drivability cannot be sufficiently addressed.
It is therefore an object of the present invention to provide a controller for an internal combustion engine, capable of assuring stable drivability by stabilizing combustion under various operating conditions.
To achieve these and other objects, a controller for an internal combustion engine of the present invention detects a combustion state of an internal combustion engine by combustion state detecting means and, when combustion becomes unstable, executes combustion stabilizing control with a combustion stabilizing control means. As such, at least the combustion velocity or combustion pressure is controlled to stabilize combustion. The combustion velocity and the combustion pressure are parameters which have the greatest effect on combustion stabilization. Therefore, when combustion becomes unstable, by controlling the combustion velocity and the combustion pressure to stabilize combustion according to the operating conditions at that time, combustion can be stabilized under various operating conditions. Thus, stable drivability is assured.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.